POISONING AND FADING PHENOMENA IN THE GRAIN REFINEMENT OF Al AND ITS ALLOYS

摘要

The present paper reviews the grain refinement experiments conducted in the author's laboratory to understand the poisoning and fading phenomena in the grain refinement of Al and its alloys. The dissolution and settling behavior of TiAl_3, TiB_2, and TiC particles in Al melt, which cause fading during grain refinement, has been studied in detail. The poisoning effect of the alloying elements such as Cr, Zr and high level of Si with Al-5Ti-1B master alloy as grain refiner has been demonstrated. Boron rich master alloys such A1-3B and Al-1Ti-3B and newly developed Al-Ti-C master alloys are found to be more effective grain refiners for Al-Si alloys compared to the conventional Al-5Ti-1B master alloys.